Optical scanner, image display apparatus, and head-mount display

ABSTRACT

An optical scanner includes: a base portion; a light reflecting portion that reflects light; a connection portion that connects the base portion and the light reflecting portion; and a shaft portion that supports the base portion in a swingable manner, wherein the light reflecting portion is disposed so that a geometrical center of the light reflecting portion is separated from a geometrical center of the base portion in a plan view, and wherein the light reflecting portion includes a center of gravity adjusting portion that performs adjustment so that a distance between the geometrical center of the base portion and a center of gravity of the light reflecting portion in the plan view becomes smaller than a distance between the geometrical center of the light reflecting portion and the geometrical center of the base portion in the plan view.

BACKGROUND

1. Technical Field

The present invention relates to an optical scanner, an image displayapparatus, and a head-mount display.

2. Related Art

For example, as an image display apparatus such as a head-mount display,a projector, or the like, an optical scanner that performs 2-dimensionalscanning with light may be included.

An optical scanner according to JP-A-2009-75587 includes a frame, anouter driving portion that is suspended to the frame through a firsttorsion spring and that can rotate about a first axis, an inner drivingportion that is suspended to the outer driving portion through a secondtorsion spring, and that can rotate about a second axis orthogonal tothe first axis, and a stage that is arranged on the upper portion of theinner driving portion, and rotates together with the inner drivingportion.

In the optical scanner according to JP-A-2009-75587, the outer drivingportion is rotated about the first axis, and also the inner drivingportion is rotated about the second axis by Lorentz force generated byelectric currents that flow through coils provided respectively in theinner driving portion and the outer driving portion and a magnetic fieldbetween a pair of magnets arranged on both sides of the frame.Accordingly, scanning is performed by reflecting light on a mirrorsurface formed on the stage.

Here, the stage is formed in a disk shape, is linked to the innerdriving portion through a linking portion protruding so that the centerof the stage and the central axis are identical to each other, and isarranged so as to be symmetrical with respect to the first axis and thesecond axis, respectively, in the plan view.

However, in this optical scanner, light is generally incident in adirection inclined to the mirror surface, and the spot shape of thelight in the mirror surface forms an elliptical (oval) shape.

Accordingly, in an optical scanner disclosed in JP-A-2009-75587, thereis a problem in that the mirror surface has an unnecessary region thatis not used in the light reflection, or a portion of light is notincident on the mirror surface and is wasted.

SUMMARY

An advantage of some aspects of the invention is to provide an opticalscanner, an image display apparatus, and a head-mount display that canrealize the stable swing of the light reflecting portion, and that canform the light reflecting portion to have a plan view shape in which theutilization efficiency of the light reflection is high.

An aspect of the invention is directed to an optical scanner including abase portion; a light reflecting portion that reflects light; aconnection portion that connects the base portion and the lightreflecting portion; and a shaft portion that supports the base portionin a swingable manner. The light reflecting portion is disposed so thata geometrical center of the light reflecting portion is separated from ageometrical center of the base portion in a plan view seen in adirection in which the light reflecting portion and the base portion arelined up. The light reflecting portion includes a center of gravityadjusting portion that performs adjustment so that a distance betweenthe geometrical center of the base portion and a center of gravity ofthe light reflecting portion in the plan view becomes smaller than adistance between the geometrical center of the light reflecting portionand the geometrical center of the base portion in the plan view.

According to the optical scanner described above, the balance of themoment of inertia of the light reflecting portion about the swing axisis improved, so that the stable swing of the light reflecting portion isrealized, and the light reflecting portion can be formed to have theplan view shape in which an unnecessary region which is not used in thelight reflection is small (in which the utilization efficiency of thelight reflection is high).

Another aspect of the invention is directed to an optical scannerincluding a base portion; a light reflecting portion that reflectslight; a connection portion that connects the base portion and the lightreflecting portion; a frame body portion that is disposed to surroundthe base portion; a first shaft portion that connects the base portionand the frame body portion, and supports the base portion about a firstaxis in a swingable manner; and a second shaft portion that supports theframe body portion in a swingable manner about a second axisintersecting the first axis. The light reflecting portion is disposed sothat a geometrical center of the light reflecting portion is positionedto be separated from a geometrical center of the base portion in a planview seen in a direction in which the light reflecting portion and thebase portion are lined up. The light reflecting portion includes acenter of gravity adjusting portion that performs adjustment so that adistance between the geometrical center of the base portion and a centerof gravity of the light reflecting portion in the plan view becomessmaller than a distance between the geometrical center of the lightreflecting portion and the geometrical center of the base portion in theplan view.

In the optical scanner described above, the balance of the moment ofinertia of the light reflecting portion about the swing axis can beimproved, so that the stable swing of the light reflecting portion isrealized, and the light reflecting portion can be formed to have a planview shape in which an unnecessary region which is not used in the lightreflection is small (in which the utilization efficiency of the lightreflection is high).

Light is generally incident in a direction inclined to a reflectingsurface of the light reflecting portion. However, in a biaxial-typeoptical scanner in which the light reflecting portion swings about twoaxes, the light has to be incident to the light reflecting portion sothat highly precise light scanning is performed and an axis of the lightis identical to the intersecting point of the first axis and the secondaxis in the plan view. Therefore, if the light reflecting portion isformed to have the plan view shape in which an unnecessary region whichis not used in the light reflection is small, a geometrical center ofthe light reflecting portion is separated from a geometrical center ofthe base portion in the plan view. Further, in the biaxial-type opticalscanner, if the balance of the moment of inertia of the light reflectingportion about the swing axis (first axis or second axis) is poor, thebalance of the swinging angle of the light reflecting portion becomespoor, and undesirably bent deformation of the first shaft portion or thesecond shaft portion occurs. Therefore, in the biaxial-type opticalscanner, it is especially effective to adjust the center of gravity ofthe light reflecting portion (adjust the balance of the moment ofinertia).

In the optical scanner according to the aspect of the invention, it ispreferable that a geometrical center of the light reflecting portion isdeviated from the first axis in the plan view.

In this case, if the center of gravity is not adjusted, problems occurin that the balance of the moment of inertia of the light reflectingportion about the first axis becomes poor, the balance of the swingingangle of the light reflecting portion about the first axis becomes poor,and undesirably bent deformation of the first shaft portion occursaccording to the swing of the light reflecting portion about the secondaxis. In contrast, the aspect of the invention can prevent or suppressthe generation of the problem by adjusting the center of gravity of thelight reflecting portion by the center of gravity adjusting portion.

In the optical scanner according to the aspect of the invention, it ispreferable that a geometrical center of the light reflecting portion isdeviated from the second axis in the plan view.

In this case, if the center of gravity adjusting portion is notprovided, problems occur in that the balance of the moment of inertia ofthe light reflecting portion about the second axis becomes poor, thebalance of the swinging angle of the light reflecting portion about thesecond axis becomes poor, and undesirably bent deformation of the secondshaft portion occurs according to the swing of the light reflectingportion about the first axis. In contrast, the aspect of the inventioncan prevent or suppress the generation of the problem by adjusting thecenter of gravity of the light reflecting portion by the center ofgravity adjusting portion.

In the optical scanner according to the aspect of the invention, it ispreferable that the light reflecting portion has an elliptical or ovalshape in a direction in which the geometrical center of the lightreflecting portion and the geometrical center of the base portion arelined up in the plan view.

With this configuration, when the light is incident in the directioninclined to the reflecting surface of the light reflecting portion, itis possible to decrease the unnecessary region which is not used in thelight reflection of the light reflecting portion.

In the optical scanner according to the aspect of the invention, it ispreferable that the light reflecting portion includes a light reflectingplate of which one surface has light reflectivity, and the center ofgravity adjusting portion includes a weight that is arranged on theother surface of the light reflecting plate.

With this configuration, the process of the light reflecting platebecomes easy. The degree of freedom for adjusting the center of gravityof the light reflecting portion becomes increased.

In the optical scanner according to the aspect of the invention, it ispreferable that the weight is configured with a material different fromthat of the light reflecting plate.

It is possible to cause specific gravity of the material configuring theweight to be different from that of the material configuring the lightreflecting plate. As a result, it is possible to increase the degree offreedom for adjusting the center of gravity of the light reflectingportion.

In the optical scanner according to the aspect of the invention, it ispreferable that the weight is configured with a metallic material.

The light reflecting plate is generally configured with a siliconmaterial or a glass material, but many of the metallic materials havegreater specific gravity than silicon materials or glass materials.Therefore, it is possible to effectively adjust the center of gravity ofthe light reflecting portion by configuring the weight with a metallicmaterial.

In the optical scanner according to the aspect of the invention, it ispreferable that the center of gravity adjusting portion is configured byproviding a plurality of portions having different thicknesses to thelight reflecting plate.

With this configuration, it is possible to collectively form the centerof gravity adjusting portion while forming the light reflecting plate.Therefore, it is possible to effectively manufacture the opticalscanner.

Still another aspect of the invention is directed to an image displayapparatus including the optical scanner according to the aspect of theinvention.

With this configuration, the balance of the moment of inertia of thelight reflecting portion about the swing axis can be improved, so thatthe stable swing of the light reflecting portion is realized, and thelight reflecting portion can be formed to have a plan view shape inwhich an unnecessary region which is not used in the light reflection issmall.

Yet another aspect of the invention is directed to a head-mount displayincluding the optical scanner according to the aspect of the invention.

With this configuration, the balance of the moment of inertia of thelight reflecting portion about the swing axis can be improved, so thatthe stable swing of the light reflecting portion is realized, and thelight reflecting portion can be formed to have a plan view shape inwhich an unnecessary region which is not used in the light reflection issmall.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view illustrating an optical scanner according to afirst embodiment of the invention.

FIG. 2 is a cross-sectional view (cross-sectional view taken along Xaxis) illustrating the optical scanner illustrated in FIG. 1.

FIG. 3 is a block diagram illustrating a voltage application portion ofa driving portion included in the optical scanner illustrated in FIG. 1.

FIGS. 4A and 4B are diagrams illustrating an example of a generationvoltage in a first voltage generating circuit and a second voltagegenerating circuit illustrated in FIG. 3.

FIG. 5 is a plan view illustrating the light reflecting plate includedin the optical scanner illustrated in FIG. 1.

FIGS. 6A and 6B are diagrams illustrating the light reflecting plateincluded in the optical scanner illustrated in FIG. 1, of which FIG. 6Ais a cross-sectional view taken along the Y axis, and FIG. 6B is a rearview illustrating the light reflecting plate.

FIG. 7A is a diagram illustrating utilization efficiency of light of thelight reflecting plate in the related art, and FIG. 7B is a diagramillustrating the utilization efficiency of light of the light reflectingplate included in the optical scanner illustrated in FIG. 1.

FIGS. 8A and 8B are diagrams illustrating a light reflecting plateincluded in an optical scanner according to a second embodiment of theinvention, of which FIG. 8A is a cross-sectional view taken along the Yaxis, and FIG. 8B is a rear view of the light reflecting plate.

FIGS. 9A and 9B are diagrams illustrating a light reflecting plateincluded in an optical scanner according to a third embodiment of theinvention, of which FIG. 9A is a cross-sectional view taken along the Yaxis, and FIG. 9B is a rear view illustrating the light reflectingplate.

FIG. 10 is a plan view illustrating a light reflecting plate included inan optical scanner according to a fourth embodiment of the invention.

FIG. 11 is a diagram schematically illustrating an embodiment of animage display apparatus according to the invention.

FIG. 12 is a perspective view illustrating an image display apparatusaccording to Application Example 1 of the invention.

FIG. 13 is a perspective view illustrating an image display apparatusaccording to Application Example 2 of the invention.

FIG. 14 is a perspective view illustrating an image display apparatusaccording to Application Example 3 of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, most preferred embodiments of an optical scanner, an imagedisplay apparatus, and a head-mount display according to the inventionare described with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a plan view illustrating an optical scanner according to thefirst embodiment of the invention, and FIG. 2 is a cross-sectional view(cross-sectional view taken along X axis) illustrating the opticalscanner illustrated in FIG. 1. FIG. 3 is a block diagram illustrating avoltage application portion of a driving portion included in the opticalscanner illustrated in FIG. 1. FIGS. 4A and 4B are diagrams illustratingan example of a generation voltage in a first voltage generating circuitand a second voltage generating circuit illustrated in FIG. 3.

In addition, in the description below, for convenience of explanation,an upper side of FIG. 2 is referred to as “upper”, and a lower side isreferred to as “lower”.

As illustrated in FIGS. 1 and 2, an optical scanner 1 is a biaxial-typeoptical scanner that swings a movable mirror portion 11 about two axesof an X axis and a Y axis. The optical scanner 1 includes the movablemirror portion 11, a pair of shaft portions 12 a and 12 b (first shaftportion), a frame body portion 13, two pairs of shaft portions 14 a, 14b, 14 c, and 14 d (second shaft portion), a supporting portion 15, apermanent magnet 21, a coil 31, a magnetic core 32, and a voltageapplication portion 4. Also, through not illustrated in FIGS. 1 and 2,the optical scanner 1 includes a distortion detection element 51 (firstdistortion detection element) and a distortion detection element 52(second distortion detection element) (see FIG. 5).

Here, the movable mirror portion 11 and the pair of shaft portions 12 aand 12 b configure a first vibration system that swings about the Y axis(first axis) (reciprocating movement). The movable mirror portion 11 andthe pair of shaft portions 12 a and 12 b, the frame body portion 13, thetwo pairs of shaft portions 14 a, 14 b, 14 c, and 14 d, and thepermanent magnet 21 configure a second vibration system that swingsabout the X axis (second axis) (reciprocating movement).

Also, the permanent magnet 21, the coil 31, and the voltage applicationportion 4 configure the driving portion that drives the first vibrationsystem and the second vibration system (that is, swings the movablemirror portion 11 about the X axis and the Y axis).

Hereinafter, respective portions of the optical scanner 1 aresequentially and specifically described.

The movable mirror portion 11 includes a base portion (movable portion)111, and a light reflecting plate 113 fixed to the base portion 111through a spacer 112 (connection portion).

A light reflecting surface 114 having light reflectivity is provided onthe upper surface (one surface) of the light reflecting plate 113.

The light reflecting plate 113 is separated from the shaft portions 12 aand 12 b in a plate thickness direction of the light reflecting plate113, and is overlapped with a portion of the shaft portions 12 a and 12b in the plate thickness direction of the light reflecting plate 113(that is, a direction in which the light reflecting plate 113 and thebase portion 111 are lined up) (hereinafter, simply referred to as “planview”). Accordingly, even if the area of the plate surface of the lightreflecting plate 113 is increased, the optical scanner 1 can bedownsized.

According to the present embodiment, the light reflecting plate 113 hasan ellipse or oval shape in the plan view. Accordingly, it is possibleto effectively use the light reflecting surface 114 to reflect light.Also, though it is not illustrated in FIG. 2, a center of gravityadjusting portion 115 is provided on the lower surface of the lightreflecting plate 113. Here, the light reflecting plate 113 and thecenter of gravity adjusting portion 115 configure the “light reflectingportion” (a structure configured with the light reflecting plate 113 andthe center of gravity adjusting portion 115 is simply referred to as the“light reflecting portion”). Further, the light reflecting plate 113 andthe center of gravity adjusting portion 115 are described below.

The lower surface of the light reflecting plate 113 (the other surface,a surface on the base portion 111 side of the light reflecting plate113) is fixed to the base portion 111 through the spacer 112.

The spacer 112 links (connects) the base portion 111 and the lightreflecting plate 113, and separates the light reflecting plate 113 fromthe base portion 111 in the thickness direction of the light reflectingplate 113. Accordingly, in comparatively simple and highly precisedimensional accuracy, the light reflecting plate 113 can be separatedfrom the base portion 111 in the thickness direction of the lightreflecting plate 113. In addition, it is possible to swing the lightreflecting plate 113 about the Y axis while preventing the lightreflecting plate 113 from coming into contact with the shaft portions 12a and 12 b, the frame body portion 13, and the shaft portions 14 a, 14b, 14 c, and 14 d.

The base portion 111 is positioned on the inner side from thecircumference of the light reflecting plate 113 in the plan view. If thebase portion 111 can support the light reflecting plate 113 through thespacer 112, the area of the base portion 111 in the plan view ispreferably small, if possible. Accordingly, the distance between theshaft portion 12 a and the shaft portion 12 b can be reduced whileincreasing the area of the plate surface of the light reflecting plate113.

The frame body portion 13 has a frame shape, and is provided to surroundthe base portion 111 of the movable mirror portion 11. In other words,the base portion 111 of the movable mirror portion 11 is provided on theinner side of the frame body portion 13 having a frame shape.

The frame body portion 13 is supported by the supporting portion 15through the shaft portions 14 a, 14 b, 14 c, and 14 d. The base portion111 of the movable mirror portion 11 is supported by the frame bodyportion 13 through the shaft portions 12 a and 12 b.

The length of the frame body portion 13 in the Y axis is longer thanthat in the X axis. That is, if the length of the frame body portion 13in the Y axis is a, and the length of the frame body portion 13 in the Xaxis is b, a relation of a>b is satisfied. Accordingly, the length ofthe optical scanner 1 in the X axis can be suppressed while securing thelength required in the shaft portions 12 a and 12 b.

Further, the frame body portion 13 has a form in the plan view, alongthe external shape of the structure configured with the base portion 111of the movable mirror portion 11 and the pair of shaft portions 12 a and12 b. Accordingly, the frame body portion 13 can be downsized whileallowing the vibration of the first vibration system to be configuredwith the movable mirror portion 11, and the pair of shaft portions 12 aand 12 b, that is, the swing of the movable mirror portion 11 about theY axis.

Further, the shape of the frame body portion 13 is not limited to theshape illustrated in the drawings, as long as it has a frame shape.

The shaft portions 12 a and 12 b and the shaft portions 14 a, 14 b, 14c, and 14 d can be respectively elastically deformed. Also, the shaftportions 12 a and 12 b link the movable mirror portion 11 and the framebody portion 13 so that the movable mirror portion 11 can swing (rotate)about the Y axis (first axis). In addition, the shaft portions 14 a, 14b, 14 c, and 14 d link the frame body portion 13 and the supportingportion 15 so that the frame body portion 13 can swing (rotate) aboutthe X axis (second axis) orthogonal to the Y axis.

The shaft portions 12 a and 12 b are arranged to face each other throughthe base portion 111 of the movable mirror portion 11. The shaftportions 12 a and 12 b respectively have longitudinal shapes extendingin the Y axis. One ends of the shaft portions 12 a and 12 b arerespectively connected to the base portion 111, and the other ends areconnected to the frame body portion 13. The shaft portions 12 a and 12 bare arranged so that the respective central axes are identical to the Yaxis.

The shaft portions 12 a and 12 b are respectively deformed in adistorted manner along with the swing of the movable mirror portion 11about the Y axis.

The shaft portions 14 a and 14 b and the shaft portions 14 c and 14 dare arranged to face with each other through the frame body portion 13.The shaft portions 14 a, 14 b, 14 c, and 14 d respectively havelongitudinal shapes extending in the X axis. One ends of the shaftportions 14 a, 14 b, 14 c, and 14 d are connected to the frame bodyportion 13, and the other ends are connected to the supporting portion15. The shaft portions 14 a and 14 b are provided to face each otherthrough the X axis, and the shaft portions 14 c and 14 d are provided toface each other through the X axis in the same manner.

With respect to the shaft portions 14 a, 14 b, 14 c, and 14 d, theentire shaft portions 14 a and 14 b and the entire shaft portions 14 cand 14 d are respectively deformed in a distorted manner following theswing of the frame body portion 13 about the X axis.

As described above, it is possible to swing (rotate) the movable mirrorportion 11 (in other words, the light reflecting plate 113) about twoaxes of the X axis and the Y axis orthogonal to each other by swingingthe movable mirror portion 11 about the Y axis and swinging the framebody portion 13 about the X axis.

The shapes of the shaft portions 12 a and 12 b and the shaft portions 14a, 14 b, 14 c, and 14 d are not limited to the shapes described above,and, for example, may have a bended or curved portion or a divergedportion in at least one portion in the middle.

The base portion 111, the shaft portions 12 a and 12 b, the frame bodyportion 13, the shaft portions 14 a, 14 b, 14 c, and 14 d, and thesupporting portion 15 described above are integrally formed.

According to the first embodiment, the base portion 111, the shaftportions 12 a and 12 b, the frame body portion 13, the shaft portions 14a, 14 b, 14 c, and 14 d, and the supporting portion 15 are formed byetching an SOI substrate obtained by laminating a first Si layer (devicelayer), an SiO₂ layer (box layer), and a second Si layer (handle layer),in this sequence. Accordingly, it is possible to enhance the vibrationcharacteristics of the first vibration system and the second vibrationsystem. Further, since the refined process can be performed on the SOIsubstrate by etching, it is possible to enhance the dimensional accuracyby forming the base portion 111, the shaft portions 12 a and 12 b, theframe body portion 13, the shaft portions 14 a, 14 b, 14 c, and 14 d,and the supporting portion 15 by using the SOI substrate, and it is alsopossible to downsize the optical scanner 1.

The base portion 111, the shaft portions 12 a and 12 b, and the shaftportions 14 a, 14 b, 14 c, and 14 d can be respectively configured withthe first Si layer of the SOI substrate. Accordingly, it is possible toenhance the elasticity of the shaft portions 12 a and 12 b and the shaftportions 14 a, 14 b, 14 c, and 14 d. Further, it is possible to preventthe base portion 111 from coming into contact with the frame bodyportion 13 when the base portion 111 is rotated about the Y axis.

The frame body portion 13 and the supporting portion 15 are respectivelyconfigured with a laminated body formed with the first Si layer, theSiO₂ layer, and the second Si layer of the SOI substrate. Accordingly,it is possible to enhance rigidity of the frame body portion 13 and thesupporting portion 15. Further, the SiO₂ layer and the second Si layerof the frame body portion 13 have a function as a rib increasing therigidity of the frame body portion 13, and also a function of preventingthe movable mirror portion 11 from coming into contact with thepermanent magnet 21.

Further, in the plan view, it is preferable to perform an antireflectionprocess on the upper surface of the first shaft portion, the secondshaft portion, the frame body portion 13, and the supporting portion 15which are positioned on the outer side of the light reflecting plate113. Accordingly, it is possible to prevent unnecessary light applied toportions other than the light reflecting plate 113 from becoming straylight.

The antireflection process is not particularly limited, and, forexample, forming an antireflective film (multilayered dielectric film),a roughening treatment, and a black oxide treatment may be included.

Also, configuration materials and forming methods of the base portion111, the shaft portions 12 a and 12 b, and the shaft portions 14 a, 14b, 14 c, and 14 d are provided as examples, and the invention is notlimited thereto.

According to the first embodiment, the spacer 112 and the lightreflecting plate 113 are formed by etching the SOI substrate. The spacer112 is configured with a laminated body formed with the SiO₂ layer andthe second Si layer of the SOI substrate. The light reflecting plate 113is configured with the first Si layer of the SOI substrate.

As described above, it is possible to simply and highly preciselymanufacture the spacer 112 and the light reflecting plate 113 joined toeach other by forming the spacer 112 and the light reflecting plate 113using the SOI substrate.

The spacer 112 is joined to the base portion 111 by a joining material(not illustrated) such as a bonding agent and a brazing material.

The permanent magnet 21 is joined to the lower surface of the frame bodyportion 13 (on a surface opposite to the light reflecting plate 113)described above.

The method of joining the permanent magnet 21 and the frame body portion13 is not particularly limited, but, for example, a joining method usinga bonding agent can be used.

The permanent magnet 21 is magnetized in a direction of inclining to theX axis and the Y axis in the plan view.

According to the first embodiment, the permanent magnet 21 has alongitudinal shape (cylindrical shape) extending in a direction ofinclining to the X axis and the Y axis. The permanent magnet 21 ismagnetized in a longitudinal direction thereof. That is, the permanentmagnet 21 is magnetized so that one end becomes an S pole, and the otherend becomes an N pole.

Further, the permanent magnet 21 is disposed so as to be symmetricalwith an intersecting point of the X axis and the Y axis to be thecenter, in the plan view.

In the first embodiment, a case in which one permanent magnet isdisposed in the frame body portion 13 is described, but the invention isnot limited to this, and, for example, two permanent magnets may bedisposed in the frame body portion 13. In this case, two long permanentmagnets are disposed in the frame body portion 13, so as to face eachother through the base portion 111 and to be parallel to each other inthe plan view.

An inclination angle θ of the permanent magnet 21 in the magnetizationdirection (extending direction) with the X axis is not particularlylimited, but is preferably equal to or greater than 30° and equal to orless than 60°, more preferably equal to or greater than 45° and equal toor less than 60°, and still more preferably 45°. It is possible tosmoothly and securely rotate the movable mirror portion 11 about the Xaxis by providing the permanent magnet 21.

In contrast, if the inclination angle θ is less than the lower limit,the movable mirror portion 11 may not be sufficiently rotated about theX axis according to various conditions of the strength of the voltageapplied by the voltage application portion 4 to the coil 31, or thelike. Meanwhile, if the inclination angle θ exceeds the upper limit, themovable mirror portion 11 may not sufficiently rotate about the Y axisaccording to various conditions.

As the permanent magnet 21, for example, a neodymium magnet, a ferritemagnet, a samarium-cobalt magnet, an alnico magnet, and a bonded magnetare preferably used. The permanent magnet 21 can be obtained bymagnetizing a hard magnetic body, and for example, the permanent magnet21 can be formed by providing an unmagnetized hard magnetic body in theframe body portion 13, and then magnetizing the hard magnetic body. Thisis because if the previously magnetized permanent magnet 21 is providedin the frame body portion 13, the permanent magnet 21 may not beprovided in a desired position by influences from a magnetic field ofthe outside or other components.

The coil 31 is provided right below the permanent magnet 21. That is,the coil 31 is provided so as to face the lower surface of the framebody portion 13. Accordingly, the magnetic field generated from the coil31 can be effectively applied to the permanent magnet 21. Further, thepower saving and the downsizing of the optical scanner 1 can beachieved.

According to the first embodiment, the coil 31 is disposed so as to bewound around the magnetic core 32. Accordingly, the magnetic fieldgenerated in the coil 31 can be effectively applied to the permanentmagnet 21. Further, the magnetic core 32 may be omitted.

The coil 31 is electrically connected to the voltage application portion4. Also, the magnetic field having magnetic flux orthogonal to the Xaxis and the Y axis is generated from the coil 31 by applying thevoltage to the coil 31 by the voltage application portion 4.

As illustrated in FIG. 3, the voltage application portion 4 includes afirst voltage generating circuit 41 that generates a first voltage V₁causing the movable mirror portion 11 to rotate about the Y axis, asecond voltage generating circuit 42 that generates a second voltage V₂causing the movable mirror portion 11 to rotate about the X axis, and avoltage superimposing portion 43 in which the first voltage V₁ and thesecond voltage V₂ are superimposed, and applies the voltagessuperimposed in the voltage superimposing portion 43 to the coil 31.

As illustrated in FIG. 4A, the first voltage generating circuit 41generates the first voltage V₁ (horizontal scanning voltage) thatperiodically changes in a cycle T₁. That is, the first voltagegenerating circuit 41 generates the first voltage V₁ of a firstfrequency (1/T₁).

The first voltage V₁ has a waveform similar to a sine wave. Therefore,the optical scanner 1 can effectively perform main scanning with light.Further, the waveform of the first voltage V₁ is not limited thereto.

Further, the first frequency (1/T₁) is not particularly limited as longas it is a frequency appropriate for horizontal scanning, but ispreferably 10 to 40 kHz.

According to the first embodiment, the first frequency is configured tobe identical to the torsional resonance frequency (f1) of the firstvibration system (torsional vibration system) configured with themovable mirror portion 11, and the pair of shaft portions 12 a and 12 b.That is, the first vibration system is designed (manufactured) so thatthe torsional resonance frequency f1 thereof can be the frequencyappropriate for horizontal scanning. Accordingly, it is possible toincrease the rotational angle of the movable mirror portion 11 about theY axis.

Meanwhile, as illustrated in FIG. 4B, the second voltage generatingcircuit 42 generates the second voltage V₂ (vertical scanning voltage)that periodically changes in a cycle T₂ different from the cycle T₁.That is, the second voltage generating circuit 42 generates the secondvoltage V₂ of a second frequency (1/T₂).

The second voltage V₂ has a waveform similar to a sawtooth wave.Therefore, the optical scanner 1 can effectively perform the verticalscanning (subscanning) with light. Further, the waveform of the secondvoltage V₂ is not limited thereto.

The second frequency (1/T₂) is not particularly limited, as long as itis different from the first frequency (1/T₁), and is appropriate for thevertical scanning. However, the second frequency (1/T₂) is preferably 30to 120 Hz (about 60 Hz). In this manner, it is possible to rotate themovable mirror portion 11 respectively about two axes (X axis and Yaxis) orthogonal to each other at a frequency appropriate for drawing ina display by setting the frequency of the second voltage V₂ to be about60 Hz, and the frequency of the first voltage V₁ to be 10 to 40 kHz.However, if the movable mirror portion 11 can rotate respectively aboutthe axes of the X axis and the Y axis, the combination of the frequencyof the first voltage V₁ and the frequency of the second voltage V₂ isnot particularly limited.

According to the first embodiment, the frequency of the second voltageV₂ is adjusted so as to be a frequency different from the torsionalresonance frequency (resonance frequency) of the second vibration system(torsional vibration system) configured with the movable mirror portion11, the pair of shaft portions 12 a and 12 b, the frame body portion 13,the two pairs of shaft portions 14 a, 14 b, 14 c, and 14 d, and thepermanent magnet 21.

The frequency of the second voltage V₂ (second frequency) is preferablysmaller than the frequency (first frequency) of the first voltage V₁.That is, the cycle T₂ is preferably longer than the cycle T₁.Accordingly, it is possible to more securely and smoothly rotate themovable mirror portion 11 about the Y axis at the first frequency, andalso about the X axis at the second frequency.

Further, if the torsional resonance frequency of the first vibrationsystem is f1 [Hz], and the torsional resonance frequency of the secondvibration system is f2 [Hz], f1 and f2 preferably satisfy therelationship of f2<f1, and more preferably satisfy the relationship off1≧10f2. Accordingly, it is possible to more smoothly rotate the movablemirror portion 11 at the frequency of the second voltage V₂ about the Xaxis while rotating the movable mirror portion 11 at the frequency ofthe first voltage V₁ about the Y axis. In contrary, if f1 and f2 satisfythe relationship of f1≦f2, it is possible to generate the vibration ofthe first vibration system by the second frequency.

The first voltage generating circuit 41 and the second voltagegenerating circuit 42 are respectively connected to a control portion 7,and are driven based on signals from the control portion 7. The voltagesuperimposing portion 43 is connected to the first voltage generatingcircuit 41 and the second voltage generating circuit 42.

The voltage superimposing portion 43 includes an adder 43 a for applyingthe voltage to the coil 31. The adder 43 a receives the first voltage V₁from the first voltage generating circuit 41, and also the secondvoltage V₂ of the second voltage generating circuit 42, and superimposesand applies these voltages to the coil 31.

Next, a method of driving the optical scanner 1 is described. Further,according to the first embodiment, as described above, the frequency ofthe first voltage V₁ is set to be identical to the torsional resonancefrequency of the first vibration system, and the frequency of the secondvoltage V₂ is set to be a value different from the torsional resonancefrequency of the second vibration system, and smaller than the frequencyof the first voltage V₁ (for example, the frequency of the first voltageV₁ is set to be 18 kHz, and the frequency of the second voltage V₂ isset to be 60 Hz).

For example, the optical scanner 1 superimposes the first voltage V₁illustrated in FIG. 4A and the second voltage V₂ illustrated in FIG. 4Bin the voltage superimposing portion 43, and applies the superimposedvoltage to the coil 31.

Then, a magnetic field (the magnetic field is referred to as “a magneticfield A1”) that attracts one end portion (N pole) of the permanentmagnet 21 to the coil 31 by the first voltage V₁ and separates the otherend portion (S pole) of the permanent magnet 21 from the coil 31 and amagnetic field (the magnetic field is referred to as “a magnetic fieldA2”) that separates one end portion (N pole) of the permanent magnet 21from the coil 31 and also attracts the other end portion (S pole) of thepermanent magnet 21 to the coil 31 are alternately switched.

Here, as described above, the permanent magnet 21 is arranged so thatthe respective end portions (magnetic poles) are positioned in tworegions partitioned by the Y axis. That is, in the plan view of FIG. 1,the N pole of the permanent magnet 21 is positioned on one side with theY axis interposed therebetween, and the S pole of the permanent magnet21 is positioned on the other side. Therefore, the vibrations havingvibration components around the Y axis are excited in the frame bodyportion 13 by alternately switching the magnetic field A1 and themagnetic field A2, the shaft portions 12 a and 12 b are deformed in adistorted manner along with the vibrations, and the movable mirrorportion 11 is rotated about the Y axis at the frequency of the firstvoltage V₁.

Further, the frequency of the first voltage V₁ is identical to thetorsional resonance frequency of the first vibration system. Therefore,the movable mirror portion 11 can be effectively rotated about the Yaxis by the first voltage V₁. That is, even if the vibrations having thevibration components around the Y axis of the frame body portion 13 aresmall, it is possible to increase the rotational angle of the movablemirror portion 11 about the Y axis followed by the vibrations.

Meanwhile, a magnetic field (the magnetic field is referred to as “amagnetic field B1”) that attracts one end portion (N pole) of thepermanent magnet 21 to the coil 31 by the second voltage V₂ andseparates the other end portion (S pole) of the permanent magnet 21 fromthe coil 31 and a magnetic field (the magnetic field is referred to as“a magnetic field B2”) that separates one end portion (N pole) of thepermanent magnet 21 from the coil 31 and attracts the other end portion(S pole) of the permanent magnet 21 to the coil 31 are alternatelyswitched.

Here, as described above, the permanent magnet 21 is arranged so thatthe end portions (magnetic poles) are respectively positioned in the tworegions partitioned by the X axis. That is, in the plan view of FIG. 1,the N pole of the permanent magnet 21 is positioned on one side with theX axis interposed therebetween, and the S pole of the permanent magnet21 is positioned on the other side. Therefore, the shaft portions 14 aand 14 b and the shaft portions 14 c and 14 d are respectively deformedin a distorted manner by alternately switching the magnetic field B1 andthe magnetic field B2, and the frame body portion 13 is rotated aboutthe X axis together with the movable mirror portion 11 at the frequencyof the second voltage V₂.

Further, the frequency of the second voltage V₂ is set to be extremelylower than the frequency of the first voltage V₁. In addition, thetorsional resonance frequency of the second vibration system is designedto be lower than the torsional resonance frequency of the firstvibration system. Therefore, it is possible to prevent the movablemirror portion 11 from being rotated about the Y axis at the frequencyof the second voltage V₂.

As described above, the movable mirror portion 11 can be rotated aboutthe Y axis at the frequency of the first voltage V₁ and about the X axisat the frequency of the second voltage V₂ by applying the voltageobtained by superimposing the first voltage V₁ and the second voltage V₂to the coil 31. Accordingly, it is possible to achieve the power savingand the downsizing of the apparatus, and to rotate the movable mirrorportion 11 respectively about the axes of the X axis and the Y axis bythe electromagnetic driving method (moving magnet type method).Specifically, it is possible to excite the vibrations having thevibration components around the Y axis of the frame body portion 13without applying direct driving power to the base portion 111 or thelight reflecting plate 113, and to swing the light reflecting plate 113about the Y axis along with the vibrations. Therefore, compared to thecase in which driving sources are provided respectively to the baseportion 111 and the frame body portion 13, it is possible to reduce thenumber of components (permanent magnet and coil) that configure thedriving sources. Therefore, a simple and small configuration can beachieved. Further, since the coil 31 is separated from the vibrationsystem of the optical scanner 1, it is possible to prevent an adverseeffect on the vibration system caused by the generation of heat by thecoil 31.

Such movements of the movable mirror portion 11 are detected based ondetected signals of the distortion detection elements 51 and 52.

The distortion detection element 51 (first distortion detection element)detects the deformation of the shaft portion 12 b (mainly, distorteddeformation). The detection signals of the distortion detection element51 include signals based on the distorted deformation of the shaftportion 12 b. Accordingly, the movements of the movable mirror portion11 about the Y axis can be detected based on the detection signals ofthe distortion detection element 51.

Meanwhile, the distortion detection element 52 (second distortiondetection element) detects the deformation of the shaft portion 14 d(mainly, bent deformation). The detection signals of the distortiondetection element 52 include signals based on the distorted deformationof the entire shaft portions 14 c and 14 d. Therefore, the movements ofthe movable mirror portion 11 and the frame body portion 13 about the Xaxis can be detected based on the detection signals of the distortiondetection element 52.

The distortion detection elements 51 and 52 are 2-terminal-type or4-terminal-type piezoresistive elements, respectively. Thepiezoresistive region included in the piezoresistive element is formedby doping impurities such as phosphorus or boron on the surface of theshaft portion 12 b or the supporting portion 15.

The distortion detection elements 51 and 52 are electrically connectedto the control portion 7 through wiring (not illustrated). Also, thecontrol portion 7 controls the driving of the voltage applicationportion 4 based on the detection signals of the distortion detectionelements 51 and 52.

Here, the light reflecting plate 113 is described with reference toFIGS. 5 to 7B.

FIG. 5 is a plan view illustrating the light reflecting plate includedin the optical scanner illustrated in FIG. 1. FIGS. 6A and 6B arediagrams illustrating the light reflecting plate included in the opticalscanner illustrated in FIG. 1, of which FIG. 6A is a cross-sectionalview taken along the Y axis, and FIG. 6B is a rear view illustrating thelight reflecting plate. Further, FIG. 7A is a diagram illustratingutilization efficiency of light of the light reflecting plate in therelated art, and FIG. 7B is a diagram illustrating the utilizationefficiency of light of the light reflecting plate included in theoptical scanner illustrated in FIG. 1.

As illustrated in FIG. 5, the light reflecting plate 113 is provided sothat a geometrical center P of the base portion 111 becomes a positionfar from the geometrical center g of the light reflecting plate 113 inthe plan view. Also, as illustrated in FIGS. 6A and 6B, the lightreflecting plate 113 is provided with the center of gravity adjustingportion 115.

The center of gravity adjusting portion 115 has a function of performingadjustment so that a distance between the geometrical center P of thebase portion 111 and the center of gravity G of the light reflectingportion (mass formed with the light reflecting plate 113 and the centerof gravity adjusting portion 115) in the plan view becomes smaller thana distance between the geometrical center g of the light reflectingplate 113 and the geometrical center P of the base portion 111 in theplan view. According to the first embodiment, the geometrical center Pof the base portion 111 and the center of gravity G of the lightreflecting portion are identical to each other in the plan view. Thatis, the center of gravity adjusting portion 115 adjusts the center ofgravity G of the light reflecting portion so that the distance betweenthe geometrical center P of the base portion 111 and the center ofgravity G of the light reflecting portion in the plan view becomes zero.

Here, the geometrical center g of the light reflecting plate 113 is thegeometric center of gravity in the plan view shape of the lightreflecting plate 113. The geometrical center P of the base portion 111is the geometric center of gravity in the plan view shape of the baseportion 111. Also, the center of gravity G of the light reflectingportion is the physical center of gravity (center of mass) of the lightreflecting portion.

It is possible to enhance the balance of the moment of inertia about theswing axis (the X axis and the Y axis) of the light reflecting plate113, to realize the stable swing of the light reflecting plate 113, andto form the light reflecting plate 113 to have a plan view shape with asmall unnecessary region which is not used in the light reflection(having high utilization efficiency of light reflection) by providingthe center of gravity adjusting portion 115 to the light reflectingplate 113.

As illustrated in FIG. 6A, though light LL is generally caused to beincident in a direction inclined to the light reflecting surface 114 ofthe light reflecting plate 113, especially in the biaxial-type opticalscanner 1 in which the light reflecting plate 113 swings about two axesas described above, the light LL has to be incident to the lightreflecting plate 113 so that highly precise light scanning is performedand an axis La of the light LL is identical to the intersecting point(point identical to the geometrical center P of the base portion 111according to the first embodiment) between the X axis and the Y axis inthe plan view.

As illustrated in FIG. 7A, when a movable mirror portion 11X including acircular light reflecting plate 113X in the related art is used, if thelight LL is incident in the direction inclined to a light reflectingsurface 114X of the light reflecting plate 113X so that the axis La ofthe light LL is identical to the intersecting point (the geometricalcenter P) between the X axis and the Y axis in the plan view, the lightreflecting surface 114X is caused to have a large unnecessary regionwhich is not used in the light reflection. The unnecessary regionundesirably increases the area of the light reflecting surface 114X andthe area and the volume of the light reflecting plate 113X, so that theair resistance when the light reflecting plate 113X swings is increased.As a result, the electric power consumption is increased. Also, sincethe mass of the light reflecting plate 113X is unnecessarily increased,this also causes an increase of the electric power consumption.

Therefore, as illustrated in FIG. 7B, the light reflecting plate 113 isformed to have a plan view shape in which an unnecessary region which isnot used in the light reflection is small. Here, in the plan view, thelight reflecting plate 113 is positioned so that the geometrical centerg of the light reflecting plate 113 and the geometrical center P of thebase portion 111 are separated from each other (see FIG. 6B).

According to the first embodiment, the light reflecting plate 113 has anelliptical shape or the oval shape in a direction in which thegeometrical center g of the light reflecting plate 113 and thegeometrical center P of the base portion 111 are lined up (Y axisdirection in the first embodiment) in the plan view. Accordingly, whenthe light is incident in the direction inclined to the light reflectingsurface 114 of the light reflecting plate 113, it is possible todecrease the unnecessary region which is not used in the lightreflection of the light reflecting plate 113.

In the biaxial-type optical scanner 1, if the balance of the moment ofinertia about the swing axes (X axis or Y axis) of the light reflectingplate 113 is poor, the balance of the swinging angle of the lightreflecting plate 113 becomes poor, and also undesirably bent deformationoccurs in the shaft portion 12 a or 12 b or the shaft portion 14 a, 14b, 14 c, or 14 d.

More specifically, according to the first embodiment, the geometricalcenter g of the light reflecting plate 113 is deviated from the Y axis.However, if the center of gravity adjusting portion 115 is not provided,the balance of the moment of inertia about the X axis of the lightreflecting plate 113 becomes poor, and the balance of the swinging angleabout the X axis of the light reflecting plate 113 becomes poor. Thatis, if the center of gravity of the light reflecting portion is notadjusted, the center of gravity G of the light reflecting portion isdeviated from the X axis in the plan view, and when the light reflectingplate 113 swings about the X axis, the swinging angle of the portion onthe geometrical center g side of the light reflecting plate 113 and theswinging angle of the portion on the other side with respect to the Xaxis become different from each other.

Further, as described above, since the light reflecting plate 113 isseparated from the shaft portions 12 a and 12 b in the plate thicknessdirection of the light reflecting plate 113, the center of gravity G ofthe light reflecting portion is separated from the Y axis in thethickness direction of the light reflecting plate 113. Accordingly, ifthe center of gravity of the light reflecting portion is not adjusted,undesirably bent deformation occurs in the shaft portion 14 a, 14 b, 14c, or 14 d according to the swing of the light reflecting plate 113about the Y axis. That is, if the center of gravity G of the lightreflecting portion is deviated from the X axis in the plan view, whenthe light reflecting plate 113 swings about the Y axis, the force thatcauses the base portion 111 to rotate about the axis orthogonal to the Xaxis and the Y axis is applied to the base portion 111. As a result, theundesirably bent deformation occurs in the shaft portion 12 a or 12 b,or the shaft portion 14 a, 14 b, 14 c, or 14 d.

Accordingly, in the biaxial-type optical scanner 1, it is particularlyeffective to adjust the center of gravity of the light reflectingportion. That is, it is possible to prevent or suppress the unnecessaryproblems described above from occurring by adjusting the center ofgravity G of the light reflecting portion by the center of gravityadjusting portion 115.

In the first embodiment, as illustrated in FIGS. 6A and 6B, the centerof gravity adjusting portion 115 is a weight arranged on a surfaceopposite to the light reflecting surface 114 of the light reflectingplate 113. Accordingly, the process of the light reflecting plate 113becomes easy. Also, the center of gravity adjusting portion 115 does notblock the light reflection of the light reflecting surface 114. Thedegree of freedom for adjusting the center of gravity of the lightreflecting portion becomes increased. The center of gravity adjustingportion 115 can adjust the center of gravity of the light reflectingportion by appropriately selecting a formation position, a scope, ashape, a thickness, a configuration material, or the like.

The center of gravity adjusting portion 115 is positioned on theopposite side of the geometrical center g of the light reflecting plate113 with respect to the X axis. Accordingly, the center of gravity G ofthe light reflecting portion can be brought close to the geometricalcenter P of the base portion 111. In FIGS. 6A and 6B, the center ofgravity adjusting portion 115 is formed on the entire region on theopposite side of the geometrical center g of the light reflecting plate113 in the X axis. However, as long as it has a portion provided on theopposite side of the geometrical center g of the light reflecting plate113 with respect to the X axis, the formation region of the center ofgravity adjusting portion 115 is not limited to the region asillustrated in FIGS. 6A and 6B. For example, the center of gravityadjusting portion 115 may be formed on a portion of the region on theopposite side of the geometrical center g of the light reflecting plate113 with respect to the X axis, or may have a portion formed in a regionon the geometrical center g side of the light reflecting plate 113 withrespect to the X axis.

The center of gravity adjusting portion 115 has a film shape or a layershape. Accordingly, the center of gravity adjusting portion 115 can behighly precisely formed by a film forming method.

Configuration materials of the center of gravity adjusting portion 115are not particularly limited. For example, a metallic material, a glassmaterial, a silicon material, a resin material, or the like can be used,but it is preferable to use a material different from that of the lightreflecting plate 113. It is possible to cause specific gravity of thematerial configuring a center of gravity adjusting portion to bedifferent from that of the material configuring the light reflectingplate 113 by configuring the center of gravity adjusting portion 115with a different material from that of the light reflecting plate 113.As a result, it is possible to increase the degree of freedom foradjusting the center of gravity of the light reflecting portion.

Specifically, it is preferable that the center of gravity adjustingportion 115 be configured with a metallic material. The light reflectingplate 113 is generally configured by using a silicon material or a glassmaterial, but many of the metallic materials have greater specificgravity than silicon materials or glass materials. Therefore, it ispossible to effectively adjust the center of gravity of the lightreflecting portion by configuring the center of gravity adjustingportion 115 with a metallic material. The metallic material is notparticularly limited, as long as it can form a film, and various kindsof metallic materials can be used. However, it is preferable to use amaterial which has greater specific gravity than silicon, andcomparatively higher chemical stability, for example, gold, silver,platinum, nickel, aluminum, titanium, tungsten, and chromium.

In the optical scanner 1 described above, it is possible to improve thebalance of the moment of inertia about the swing axis of the lightreflecting portion, to realize the stable swing of the light reflectingplate 113, and also to form the light reflecting plate 113 to have theplan view shape with high utilization efficiency of the light reflectionby providing the center of gravity adjusting portion 115 to the lightreflecting plate 113.

Second Embodiment

Subsequently, a second embodiment of the invention is described.

FIGS. 8A and 8B are diagrams illustrating a light reflecting plateincluded in an optical scanner according to the second embodiment of theinvention, of which FIG. 8A is a cross-sectional view taken along the Yaxis, and FIG. 8B is a rear view of the light reflecting plate.

Hereinafter, the second embodiment is described with respect to thedifference from the first embodiment described above, and detaileddescriptions of the same matters are omitted. Further, in FIGS. 8A and8B, configurations the same as the first embodiment are denoted by thesame reference numerals.

The second embodiment is the same as the first embodiment except thatthe configuration of the center of gravity adjusting portion and thelight reflecting plate is different.

As illustrated in FIGS. 8A and 8B, a movable mirror portion 11A includedin the optical scanner according to the second embodiment includes alight reflecting plate 113A (light reflecting portion).

The light reflecting plate 113A includes a thin portion 1131 and a thickportion 1132 which is thicker than the thin portion 1131, as a pluralityof portions having different thicknesses. The thin portion 1131 isprovided on the geometrical center g side of the light reflecting plate113A with respect to the X axis in the plan view, and the thick portion1132 is provided on the opposite side of the geometrical center g of thelight reflecting plate 113A with respect to the X axis in the plan view.It is possible to adjust the center of gravity G of the light reflectingportion by providing the thin portion 1131 and the thick portion 1132 tothe light reflecting plate 113A in this manner. Here, the thick portion1132 configures a center of gravity adjusting portion 115A that adjuststhe center of gravity G of the light reflecting portion. The center ofgravity adjusting portion 115A can be collectively formed together withforming the light reflecting plate 113A. Therefore, it is possible toeffectively manufacture the optical scanner. In addition, the thinportion 1131 may configure the “center of gravity adjusting portion”,and the thin portion 1131 and the thick portion 1132 may configure the“center of gravity adjusting portion”.

According to the second embodiment as described above, it is possible toimprove the balance of the moment of inertia about the swing axis of thelight reflecting portion, to realize the stable swing of the lightreflecting portion, and to form the light reflecting portion to have theplan view shape with high utilization efficiency of the lightreflection.

Third Embodiment

Subsequently, a third embodiment of the invention is described.

FIGS. 9A and 9B are diagrams illustrating a light reflecting plateincluded in an optical scanner according to the third embodiment of theinvention, FIG. 9A is a cross-sectional view taken along the Y axis, andFIG. 9B is a rear view illustrating the light reflecting plate.

Hereinafter, the third embodiment is described with respect to thedifference from the first embodiment described above, and detaileddescriptions of the same matters are omitted. Further, in FIGS. 9A and9B, configurations the same as the above embodiments are denoted by thesame reference numerals.

The third embodiment is the same as the first embodiment except that aforming position of a center of gravity adjusting portion is different.

As illustrated in FIGS. 9A and 9B, a movable mirror portion 11B includedin the optical scanner according to the third embodiment includes acenter of gravity adjusting portion 115B.

The center of gravity adjusting portion 115B is provided in the endportion on the opposite side of the geometrical center g with respect tothe X axis of the light reflecting plate 113. Since the moment ofinertia of the light reflecting portion about the swing axis isproportional to a square of a distance from the swing axis, it ispossible to effectively adjust the center of gravity of the lightreflecting portion, and to reduce the weight that configures the centerof gravity adjusting portion 115B by providing the center of gravityadjusting portion 115B in the end portion of the light reflecting plate113.

According to the third embodiment as described above, it is possible toimprove the balance of the moment of inertia about the swing axis of thelight reflecting portion, to realize the stable swing of the lightreflecting portion, and to form the light reflecting portion to have theplan view shape with high utilization efficiency of the lightreflection.

Fourth Embodiment

Subsequently, a fourth embodiment of the invention is described.

FIG. 10 is a plan view illustrating a light reflecting plate included inan optical scanner according to the fourth embodiment of the invention.

Hereinafter, the fourth embodiment is described with respect to thedifference from the first embodiment described above, and detaileddescriptions of the same matters are omitted. Further, in FIG. 10,configurations the same as the above embodiments are denoted by the samereference numerals.

The fourth embodiment is the same as the first embodiment except thatthe disposing orientation of the light reflecting plate is different.

As illustrated in FIG. 10, an optical scanner 1C according to the fourthembodiment is formed so that the geometrical center g of the lightreflecting plate 113 is deviated from the Y axis in the plan view.

In this case, if the center of gravity adjusting portion is notprovided, the balance of the moment of inertia of the light reflectingportion about the Y axis becomes poor. Therefore, there is a problem inthat the balance of the swinging angle of the light reflecting portionabout the Y axis becomes poor, and undesirably bent deformation of theshaft portions 12 a and 12 b occurs according to the swing of the lightreflecting portion about the X axis.

Here, though it is not illustrated in FIG. 10, in the same manner as thefirst embodiment described above, a center of gravity adjusting portionis provided on the lower surface of the light reflecting plate 113.Accordingly, the center of gravity of the light reflecting portion isadjusted, and the occurrence of the problem is prevented and suppressed.

According to the fourth embodiment, the balance of the moment of inertiaof the light reflecting portion about the swing axis is improved, sothat the stable swing of the light reflecting portion is realized, andthe light reflecting portion can be formed to have the plan view shapein which the utilization efficiency of the light reflection is high.

Embodiment of Image Display Apparatus

FIG. 11 is a diagram schematically illustrating an embodiment of theimage display apparatus according to the invention.

In this embodiment, an example of the image display apparatus in whichthe optical scanner 1 is used as an optical scanner of the display forimaging is described. In addition, a “longitudinal direction” of ascreen S is referred to as a “traverse direction”, and a directionperpendicular to a longitudinal direction is referred to as a “verticaldirection”. Further, the X axis is parallel to the traverse direction ofthe screen S, and the Y axis is parallel to the vertical direction ofthe screen S.

An image display apparatus (projector) 9 includes light sourceapparatuses (light sources) 91 that emit light such as laser, aplurality of dichroic mirrors 92A, 92B, and 92C, and the optical scanner1.

The light source apparatuses 91 include a red light source apparatus 911that emits red light, a blue light source apparatus 912 that emits bluelight, and a green light source apparatus 913 that emits green light.

The respective dichroic mirrors 92A, 92B, and 92C are optical elementsthat synthesize light emitted from the red light source apparatus 911,the blue light source apparatus 912, and the green light sourceapparatus 913.

The image display apparatus 9 is configured to synthesize the lightemitted from the light source apparatuses 91 (the red light sourceapparatus 911, the blue light source apparatus 912, the green lightsource apparatus 913) with the dichroic mirrors 92A, 92B, and 92C basedon the image information from a host computer (not illustrated), tocause the optical scanner 1 to perform 2-dimensional scanning with thesynthesized light, and to form a color image on the screen S.

When performing the 2-dimensional scanning, scanning (main scanning) inthe traverse direction of the screen S is performed with light reflectedfrom the light reflecting surface 114 by the rotation of the movablemirror portion 11 of the optical scanner 1 about the Y axis. Meanwhile,scanning (subscanning) in the vertical direction of the screen S isperformed with light reflected from the light reflecting surface 114 bythe rotation of the movable mirror portion 11 of the optical scanner 1about the X axis.

Meanwhile, in FIG. 11, after the optical scanner 1 performs the2-dimensional scanning with the light synthesized by the dichroicmirrors 92A, 92B, and 92C, the light is reflected from a fixed mirror93, and an image is formed on the screen S. However, it is possible toomit the fixed mirror 93, and apply the light obtained by the opticalscanner 1 performing the 2-dimensional scanning directly to the screenS.

Since the image display apparatus 9 described above includes the opticalscanner 1, downsizing can be obtained, and start-up time can beshortened.

Hereinafter, the application example of the image display apparatus isdescribed.

Application Example 1 of Image Display Apparatus

FIG. 12 is a perspective view illustrating the image display apparatusaccording to Application Example 1 of the invention.

As illustrated in FIG. 12, the image display apparatus 9 is applied to aportable image display apparatus 100.

The portable image display apparatus 100 includes a housing 110 formedinto a dimension that can be gripped by hand and the image displayapparatus 9 embedded in the housing 110. For example, a predeterminedimage can be displayed on a predetermined surface such as a screen or adesktop by the portable image display apparatus 100.

Further, the portable image display apparatus 100 includes a display 120that displays predetermined information, a keypad 130, an audio port140, a control button 150, a card slot 160, and an AV port 170.

Further, the portable image display apparatus 100 may have otherfunctions such as a telephone communication function, and a GPSreception function.

Application Example 2 of Image Display Apparatus

FIG. 13 is a perspective view illustrating an image display apparatusaccording to Application Example 2 of the invention.

As illustrated in FIG. 13, the image display apparatus 9 can be appliedto a head-up display system 200.

In the head-up display system 200, the image display apparatus 9 ismounted on a dashboard of a vehicle, to configure a head-up display 210.It is possible to display a predetermined image such as a guide displayto a destination on a windshield 220, by the head-up display 210.

Also, the head-up display system 200 is not limited to a vehicle, andcan be also applied to an airplane, a vessel, or the like.

Application Example 3 of Image Display Apparatus

FIG. 14 is a perspective view illustrating an image display apparatusaccording to Application Example 3 of the invention.

As illustrated in FIG. 14, the image display apparatus 9 is applied to ahead-mount display 300.

That is, the head-mount display 300 includes glasses 310, and the imagedisplay apparatus 9 mounted on the glasses 310. Also, a predeterminedimage to be recognized by one eye is displayed on a display portion 320disposed in a portion which is originally a lens of the glasses 310 bythe image display apparatus 9.

The display portion 320 may be transparent, or may be opaque. If thedisplay portion 320 is transparent, it is possible to add and useinformation from the image display apparatus 9 to information from anactual world.

In addition, it is possible to provide two image display apparatuses 9with the head-mount display 300, and to display an image to berecognized by both eyes on two display portions.

In the above, the optical scanner, the image display apparatus, and thehead-mount display according to the invention are described based on theembodiments as illustrated, but the invention is not limited thereto.For example, in the optical scanner, the image display apparatus, andthe head-mount display according to the invention, configurations of therespective portions can be substituted to arbitrary configurationshaving the same function, or other configurations can be added.

The invention may be embodied by combining two arbitrary configurations(characteristics) among the respective embodiments described above.

In the embodiments described above, a case in which two (one pair) offirst shaft portions are provided is described, but the invention is notlimited thereto. For example, four (two pairs) of first shaft portionsmay be provided.

In the embodiments described above, a case in which four (two pairs) ofsecond shaft portions are provided is described, but the invention isnot limited thereto. For example, two (one pair) of second shaftportions or six (three pairs) or more of second shaft portions may beprovided.

In the embodiments described above, an example in which the lightreflecting plate covers a portion of the first shaft portion in the planview is described, but the size of the light reflecting plate is notlimited to the aforementioned embodiments. For example, the lightreflecting plate may be formed to cover the frame body portion or thesecond shaft portion.

In the embodiments described above, an example in which the lightreflecting plate and the spacer are formed by processing the SOIsubstrate is described, but the invention is not limited thereto. Forexample, the light reflecting plate and the spacer may be formed byother substrates, and the light reflecting plate and the spacer may beintegrally formed by processing a substrate of a single material such asa silicon substrate, or a glass substrate.

The spacer between the light reflecting plate and the base portion maybe a solder ball. In this case, for example, metal films are formedrespectively on surfaces of the light reflecting plate and the baseportion on the spacer side, and the metal films are joined with eachother through the solder ball.

In the embodiments described above, an example in which a driving forceis directly applied only to the frame body portion is described, but thedriving force may be directly applied respectively to the frame bodyportion and the movable portion to swing the light reflecting plateabout the first axis and the second axis. Even in this case, it ispossible to obtain the effect of preventing or suppressing unnecessaryvibrations of the light reflecting plate caused by unnecessaryvibrations transmitted from the frame body portion to the movableportion through the first shaft portion.

In the embodiments described above, an example in which a moving magnetmethod is used as a method of driving the optical scanner is described,but the invention is not limited thereto. For example, a moving coilmethod, a piezoelectric drive method, an electrostatic drive method, orthe like is used.

The entire disclosure of Japanese Patent Application No. 2013-268714,filed Dec. 26, 2013 is expressly incorporated by reference herein.

What is claimed is:
 1. An optical scanner comprising: a base portion; alight reflecting portion that reflects light; a connection portion thatconnects the base portion and the light reflecting portion; and a shaftportion that supports the base portion in a swingable manner, whereinthe light reflecting portion is disposed so that a geometrical center ofthe light reflecting portion is separated from a geometrical center ofthe base portion in a plan view seen in a direction in which the lightreflecting portion and the base portion are lined up, and wherein thelight reflecting portion includes a center of gravity adjusting portionthat performs adjustment so that a distance between the geometricalcenter of the base portion and a center of gravity of the lightreflecting portion in the plan view becomes smaller than a distancebetween the geometrical center of the light reflecting portion and thegeometrical center of the base portion in the plan view.
 2. An opticalscanner comprising: a base portion; a light reflecting portion thatreflects light; a connection portion that connects the base portion andthe light reflecting portion; a frame body portion that is disposed tosurround the base portion; a first shaft portion that connects the baseportion and the frame body portion, and supports the base portion abouta first axis in a swingable manner; and a second shaft portion thatsupports the frame body portion in a swingable manner about a secondaxis intersecting the first axis, wherein the light reflecting portionis disposed so that a geometrical center of the light reflecting portionis positioned to be separated from a geometrical center of the baseportion in a plan view seen in a direction in which the light reflectingportion and the base portion are lined up, and wherein the lightreflecting portion includes a center of gravity adjusting portion thatperforms adjustment so that a distance between the geometrical center ofthe base portion and a center of gravity of the light reflecting portionin the plan view becomes smaller than a distance between the geometricalcenter of the light reflecting portion and the geometrical center of thebase portion in the plan view.
 3. The optical scanner according to claim2, wherein the geometrical center of the light reflecting portion isdeviated from the first axis in the plan view.
 4. The optical scanneraccording to claim 2, wherein the geometrical center of the lightreflecting portion is deviated from the second axis in the plan view. 5.The optical scanner according to claim 1, wherein the light reflectingportion has an elliptical or oval shape in a direction in which thegeometrical center of the light reflecting portion and the geometricalcenter of the base portion are lined up in the plan view.
 6. The opticalscanner according to claim 1, wherein the light reflecting portionincludes a light reflecting plate of which one surface has lightreflectivity, and wherein the center of gravity adjusting portionincludes a weight that is arranged on the other surface of the lightreflecting plate.
 7. The optical scanner according to claim 6, whereinthe weight is configured with a material different from that of thelight reflecting plate.
 8. The optical scanner according to claim 7,wherein the weight is configured with a metallic material.
 9. Theoptical scanner according to claim 6, wherein the center of gravityadjusting portion is configured by providing a plurality of portionshaving different thicknesses to the light reflecting plate.
 10. An imagedisplay apparatus comprising: the optical scanner according to claim 1.11. An image display apparatus comprising: the optical scanner accordingto claim
 2. 12. An image display apparatus comprising: the opticalscanner according to claim
 3. 13. An image display apparatus comprising:the optical scanner according to claim
 4. 14. An image display apparatuscomprising: the optical scanner according to claim
 5. 15. An imagedisplay apparatus comprising: the optical scanner according to claim 6.16. A head-mount display comprising: the optical scanner according toclaim
 1. 17. A head-mount display comprising: the optical scanneraccording to claim
 2. 18. A head-mount display comprising: the opticalscanner according to claim
 3. 19. A head-mount display comprising: theoptical scanner according to claim
 4. 20. A head-mount displaycomprising: the optical scanner according to claim 5.